The present invention generally relates to a power transmission whereby the input speed, from a constant velocity, prime mover, such as an automotive engine, or any other suitable power source, may be reduced to a desired output speed by the internal workings of the transmission.
More specifically the present invention relates to an infinitely variable ratio drive mechanism, of the endless belt type, having a pair of rotating conical members configured to have parallel longitudinal axis with the smaller diameter of one conical member adjacent to the larger diameter of the other. An endless, inextensible, belt encircles and drivingly engages both conical members whereby power may be transmitted from one conical member to the other. A variable speed reduction, between the conical members, is obtained by selectively moving the endless belt along the longitudinal axis of the conical members during power transmission.
It has been well known to use opposing conical members as the driving member and the driven member in power transmissions as evidenced by the following U.S. Pat. Nos. 944,585; 2,801,547; 3,021,717; 3,906,809; 4,842,569; and 5,226,854.
All of the above references employ conical members having a single fixed, conical angle. However, as the belt or chain moves axially away from the longitudinal center, where the cone diameters are equal, the total peripheral belt length required to encircle the conical members increases as a function of the axial distance from the longitudinal center. Therefore, either the belt must be elastic or some other means must be employed to accommodate the inherent peripheral variation. Providing an elastic belt results in losses of power transmission efficiencies Therefore, some other mechanical solution is preferred.
The present invention relieves the belt length problem by providing conical members having, at least, two conical angles. A first cone angle is employed from the large diameter end of the conical member to its mid longitudinal position, and a second, slightly larger cone angle is employed from the mid point of the conical member to its small diameter end. Alternatively the conical surface of the conical members may be replaced with a curved surface whereby the peripheral length of the drive belt is constant for all positions along the longitudinal length of the drive members.
Further the present invention teaches novel, free floating sprocket bars spaced about the periphery of the conical members and extending longitudinally (axially) along the surface thereof. The sprocket bars generally parallel the surface of the conical members. However, the sprocket bars may take any other convenient shape, such as a convex configuration, as described further below. By being free floating, the sprocket bars freely move diametrically and circumferentially whereby they may fully engage a beaded or other suitably configured and generally inelastic, inextensible drive chain.